Phil Taylor or
Michael van Gerwen, who is the best player of all time. Christopher Kempf, who keeps track of all kinds of data and statistics for the PDC has done an analysis of their performances at the peak moment of their careers.
Comparing the performances of Michael van Gerwen and Phil Taylor has always been a difficult task, as they were only active for a short time in the same era. Therefore, Kempf analysed the performances of their best period. For Taylor, that was in TV tournaments between 2009 and 2011. As for Van Gerwen, it is about TV tournaments between 2015 and 2017.
From the statistics (you can look at this in detail below), it is difficult to tell who is now the best of all time. Their overall average hardly differs. Taylor's doubles percentage is just a bit higher, but then again Van Gerwen's scoring ability is slightly better.
Rivalry
Kempf therefore observes that had Taylor been born six years later or Van Gerwen six years earlier, we could have enjoyed years of unparalleled rivalry and hugely superior matches between the two rivals.